<template>
  <div class="spec-preview" ref='even'>
    <img :src="imgObj.imgUrl" />
    <div class="event" @mousemove="handler" >
    </div>
    <div class="big">
      <img :src="imgObj.imgUrl"  ref='big'/>
    </div>
    <div class="mask" ref='mask'></div>
  </div>
</template>
<script>
export default {
  name: "Zoom",
  // props接收自定义事件参数到子组件中
  props: ["skuImageList"],
  data() {
    return {
      curentIndex: 1,
    };
  },

  computed: {
    //计算属性:将组件数据进行简单的计算处理
    imgObj() {
      return this.skuImageList[this.curentIndex] || {};
    },
  },
  mounted(){
    // 全局事件总线，获取兄弟组件传递过来的索引值
    this.$bus.$on("getIndex", (index) => {
      this.curentIndex = index;
    });
  },
  methods: {
  //放大图中的盒子拖拽事件
    handler(event) {
let even=this.$refs.even     
let mask=this.$refs.mask;
let big=this.$refs.big
let W=even.offsetWidth
let H=even.offsetHeight
let w=mask.offsetWidth
let h=mask.offsetHeight
let left=event.offsetX-w/2
let top=event.offsetY-h/2
// 移动范围
if(left<=0){
  left=0
}else if(left>W-w){
left=W-w
}else if(top<=0){
  top=0
}else if(top>=H-h){
  top=H-h
}
  mask.style.left=left+'px'
  mask.style.top=top+'px'  
  big.style.left=-2*left+'px'
  big.style.top=-2*top+'px'
    },
  },
};
</script>

<style lang="scss">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>